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Biomedical subjects

P M Wortman

Publications and source records attributed to P M Wortman.

9 recordsLinked to original sources
PubMed1993

Carotid endarterectomy for asymptomatic patients. Assessing results of a quantitative synthesis.

Carotid endarterectomy (CE) surgery for asymptomatic patients remains controversial despite hundreds of published studies and recent randomized trials. Safety and efficacy are assessed using a quantitative synthesis method derived from meta-analysis and a "critical multiplist" inference approach. In addition, multivariate analyses reveal that use of a surgical shunt could further improve CE outcomes. Methods are examined for both their "confirmatory" and "exploratory" value.

Arteriosclerosis↗
PubMed1988

Inborn/outborn status and neonatal survival: a meta-analysis of non-randomized studies.

We have applied meta-analysis to investigate the relationship between birth place and the likelihood of neonatal survival, for infants of low birth weight (less than 2501 grams) in a series of 19 non-randomized studies. This paper illustrates the utility meta-analysis in evaluating medical technologies described in non-randomized studies, if proper attention is given to biases in those studies. The results of this meta-analysis show strong preferences for inborn status, especially for infants who weigh 1001-2000 grams. For infants of lower or higher birth weight (that is, less than 1001 or greater than 2000 grams), the studies are inconsistent: some favour inborn status while others favour outborn status. This heterogeneity is not surprising, because selection bias is more problematic in studies of infants at these birth weights. We discuss potential causes of and solutions to selection bias and illustrate its potential magnitude by introducing the bias factor, which should be considered in the design of future studies. When selection bias cannot be ruled out, the results shown for those who weigh 1001-2000 grams are more appropriate for generating valid conclusions and subsequent policies regarding birth place preference for low birth weight infants.

Birth Weight↗
PubMed1988

Do consensus conferences work? A process evaluation of the NIH Consensus Development Program.

The purpose of this evaluation study is to identify problems and suggest modifications in the NIH Consensus Development Program. The current program consists of three-day conferences in which experts assess medical technologies for issues of efficacy, safety, conditions of use, and other related topics (e.g., costs and social impact). Eight consensus conferences held between 1980 and 1982 were studied in depth using a variety of methods; five of the conferences were investigated concurrently. In addition, archival material was examined for all but one of the 33 conferences held up to that time, and four planning meetings for future conferences were observed. The delay in publishing our findings provided an opportunity to examine the changes introduced by NIH; it also allowed us to avoid the criticism of numerous prior evaluations for finding fault with programs that are still developing. NIH adopted many of the recommendations in our evaluation report and has investigated others. Based on our evaluation and more recent evidence, however, we conclude that the major problem that was uncovered--selection bias, particularly with respect to the choice of questions and panelists--remains a significant threat to the credibility of the consensus process. More specifically, the results indicate that controversial issues cannot be properly addressed within the present conference format, although that was one of its major purposes. Recommendations for improving the consensus process are presented, as are their implications for a larger set of consensus activities that are currently being conducted.

Consensus Statements as Topic↗
PubMed1987

Evaluating the effectiveness of neonatal intensive care. What can the literature tell us?

This article reviews the characteristics of 69 clinical research studies of the effectiveness of neonatal intensive care (NIC). Emphasis is on the availability of important information in the studies, and on their scientific quality. The analysis suggests that these studies cannot answer several of the most important questions about the usefulness of NIC, because of poor study design or implementation. Guidelines for assessing the usefulness of existing studies and suggestions for future research are provided.

Critical Care↗
PubMed1985

Cumulating quality of life results in controlled trials of coronary artery bypass graft surgery.

Many studies evaluating the effectiveness of coronary artery bypass graft surgery allude to the quality of life benefit resulting from surgery. However, no comprehensive empirical estimate of the absolute or relative magnitude of this benefit is currently available. This paper presents a data synthesis of the research literature on bypass surgery to derive such an estimate. It uses follow-up measures of the percent of patients who were angina-free within both the surgical and medical groups of 14 controlled trials to estimate the quality of life benefit following surgery. Results based on the longest reported follow-up period suggest that the chances are approximately 25 to 40% greater that patients will be angina-free if they receive surgery rather than medical treatment. Estimates of benefit are about 15% less in randomized controlled trials compared to controlled trials that used a matching strategy. These results are unlikely to be affected by related factors such as the percentage of patients who crossover from the medical group to the surgical group or the specific method of calculating anginal relief used in this research report. However, differential patients selection may account for the observed design effect.

Angina Pectoris↗
PubMed1985

Group decision making by experts: field study of panels evaluating medical technologies.

Decision-making processes and their outcomes were investigated in six consensus development conferences at the National Institutes of Health in which panels of experts evaluated new medical technologies. One hundred seventy-seven self-administered questionnaires were obtained from participants in these conferences. Questionnaire data were analyzed along with data derived from content analyses of the six consensus statements (CS) produced by the conferences. Results of these analyses provide considerable support for the hypotheses that the quality of the outcome (i.e., the CS) is determined by the existence of an interaction process, a decision procedure, and a chairperson, which facilitate the exchange of relevant information. Strong disagreements among the panelists appear to inhibit such exchange and harm the quality of the CS. Personal satisfaction appears to be more strongly related to the quality of the process and of the information disseminated than to the quality of the outcome. A clear relation was found between the panelists' status and expertise, their participation in the process, and their contribution to the CS. The pattern of these findings is quite similar to that obtained in laboratory studies. The role of preconference organizational factors, such as the selection of conference questions, panel, and speakers, and the characteristics of the technology are discussed.

Decision Making↗
PubMed1982

Medical information systems: assessing impact in the areas of hypertension, obesity and renal disease.

This study described the influence of a computerized medical record summary system in three disease areas (hypertension, obesity and renal disease) observed in the course of a controlled, randomized and prospective study of 479 Northwestern University Clinic patients. Experimental patients, who had available automated record summaries, and control patients, who had available only the manual record, were compared on several medical tests and procedures whose yearly occurrence was considered good medical practice for this patient population, and were compared as well as several measures of outcome of medical care. Evidence suggesting better care and outcome of care among patients with computerized record summaries available is presented.

Computers↗